Shell type needle bearings capable of receiving high load despite of its small bearing projected area, and having high rigidity are used in some applications as bearings that support a camshaft or a crankshaft. Halved outer rings formed by dividing an annular outer ring into halves and having a substantially semicylindrical shape are sometimes used as outer rings included in the shell type needle bearings. In such a shell type needle bearing, a single annular outer ring can be formed by fitting a pair of halved outer rings on the outer diameter side of a shaft (a rotary shaft), and causing abutting portions located at respective circumferential ends of the halved outer rings to abut on each other. In the shell type needle bearings having such a configuration, the outer ring can be fitted on the shaft with an improved fitting property.
Roller bearings having such halved outer rings are disclosed in U.S. Pat. No. 1,921,488 (Patent Literature 1), Japanese Patent Publication No. 2005-90696 of Unexamined Applications (Patent Literature 2), Japanese Patent Publication No. 2005-180459 of Unexamined Applications (Patent Literature 3), Japanese Patent Publication No. 2005-337352 of Unexamined Applications (Patent Literature 4), and Japanese National Publication No. 2002-525533 (Patent Literature 5).
In Patent Literature 1, a single annular outer ring is formed by combining a first halved outer ring with a second halved outer ring. The first halved outer ring has, at both circumferential ends thereof, V-shaped abutting portions protruding in the circumferential direction, and the second halved outer ring has, at both circumferential ends thereof, V-shaped abutting portions recessed in the circumferential direction.
In Patent Literatures 2 and 3, a race plate (a halved outer ring) has one circumferential end having a wedge shape as one abutting portion, and the other circumferential end having a valley shape as the other abutting portion. A cylindrical outer race is formed by a pair of such race plates by combining the wedge-shaped abutting portion of one of the race plates with the valley-shaped abutting portion of the other race place, and combining the valley-shaped abutting portion of the one race plate with the wedge-shaped abutting portion of the other race plate. That is, the pair of race plates have the same shape in Patent Literatures 2 and 3.
In Patent Literature 4, a halved outer ring has one circumferential end formed in protruding and recessed shapes having an inclined portion that is inclined with respect to a line extending along the axial direction, and an inclined portion that is inclined in the opposite direction from the inclined portion. An annular outer ring is formed by causing the respective protruding and recessed shapes of the pair of halved outer rings to abut on each other. In Patent Literature 4 as well, the pair of halved outer rings have the same shape. Note that the outer diameter surface of each halved outer ring is an arc-shaped surface having neither a protrusion nor a recess. In Patent Literature 5, a first halved outer ring has protrusions formed at its one circumferential end, and a second halved outer ring has cutouts formed at its one circumferential end, so that the protrusions are elastically snap-engaged with the cutouts. Note that the other circumferential ends of the first and second halved outer rings are coupled together in advance.